tor-browser

OverscrollHandoffState.cpp (7225B)

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "OverscrollHandoffState.h"

#include <algorithm>  // for std::stable_sort
#include "mozilla/Assertions.h"
#include "AsyncPanZoomController.h"

namespace mozilla {
namespace layers {

OverscrollHandoffChain::~OverscrollHandoffChain() = default;

void OverscrollHandoffChain::Add(AsyncPanZoomController* aApzc) {
 mChain.push_back(aApzc);
}

const RefPtr<AsyncPanZoomController>& OverscrollHandoffChain::GetApzcAtIndex(
   uint32_t aIndex) const {
 MOZ_ASSERT(aIndex < Length());
 return mChain[aIndex];
}

uint32_t OverscrollHandoffChain::IndexOf(
   const AsyncPanZoomController* aApzc) const {
 uint32_t i;
 for (i = 0; i < Length(); ++i) {
   if (mChain[i] == aApzc) {
     break;
   }
 }
 return i;
}

void OverscrollHandoffChain::ForEachApzc(APZCMethod aMethod) const {
 for (uint32_t i = 0; i < Length(); ++i) {
   (mChain[i]->*aMethod)();
 }
}

bool OverscrollHandoffChain::AnyApzc(APZCPredicate aPredicate) const {
 MOZ_ASSERT(Length() > 0);
 for (uint32_t i = 0; i < Length(); ++i) {
   if ((mChain[i]->*aPredicate)()) {
     return true;
   }
 }
 return false;
}

void OverscrollHandoffChain::FlushRepaints() const {
 ForEachApzc(&AsyncPanZoomController::FlushRepaintForOverscrollHandoff);
}

void OverscrollHandoffChain::CancelAnimations(
   CancelAnimationFlags aFlags) const {
 MOZ_ASSERT(Length() > 0);
 for (uint32_t i = 0; i < Length(); ++i) {
   mChain[i]->CancelAnimation(aFlags);
 }
}

void OverscrollHandoffChain::ClearOverscroll() const {
 ForEachApzc(&AsyncPanZoomController::ClearOverscroll);
}

void OverscrollHandoffChain::SnapBackOverscrolledApzc(
   const AsyncPanZoomController* aStart) const {
 uint32_t i = IndexOf(aStart);
 for (; i < Length(); ++i) {
   AsyncPanZoomController* apzc = mChain[i];
   if (!apzc->IsDestroyed()) {
     apzc->SnapBackIfOverscrolled();
   }
 }
}

void OverscrollHandoffChain::SnapBackOverscrolledApzcForMomentum(
   const AsyncPanZoomController* aStart,
   const ParentLayerPoint& aVelocity) const {
 uint32_t i = IndexOf(aStart);
 for (; i < Length(); ++i) {
   AsyncPanZoomController* apzc = mChain[i];
   if (!apzc->IsDestroyed()) {
     apzc->SnapBackIfOverscrolledForMomentum(aVelocity);
   }
 }
}

bool OverscrollHandoffChain::CanBePanned(
   const AsyncPanZoomController* aApzc) const {
 // Find |aApzc| in the handoff chain.
 uint32_t i = IndexOf(aApzc);

 // See whether any APZC in the handoff chain starting from |aApzc|
 // has room to be panned.
 for (uint32_t j = i; j < Length(); ++j) {
   if (mChain[j]->IsPannable()) {
     return true;
   }
 }

 return false;
}

bool OverscrollHandoffChain::CanScrollInDirection(
   const AsyncPanZoomController* aApzc, ScrollDirection aDirection) const {
 // Find |aApzc| in the handoff chain.
 uint32_t i = IndexOf(aApzc);

 // See whether any APZC in the handoff chain starting from |aApzc|
 // has room to scroll in the given direction.
 for (uint32_t j = i; j < Length(); ++j) {
   if (mChain[j]->CanScroll(aDirection)) {
     return true;
   }
 }

 return false;
}

bool OverscrollHandoffChain::HasOverscrolledApzc() const {
 return AnyApzc(&AsyncPanZoomController::IsOverscrolled);
}

bool OverscrollHandoffChain::HasFastFlungApzc() const {
 return AnyApzc(&AsyncPanZoomController::IsFlingingFast);
}

bool OverscrollHandoffChain::HasAutoscrollApzc() const {
 return AnyApzc(&AsyncPanZoomController::IsAutoscroll);
}

RefPtr<AsyncPanZoomController> OverscrollHandoffChain::FindFirstScrollable(
   const InputData& aInput, ScrollDirections* aOutAllowedScrollDirections,
   IncludeOverscroll aIncludeOverscroll) const {
 // Start by allowing scrolling in both directions. As we do handoff
 // overscroll-behavior may restrict one or both of the directions.
 *aOutAllowedScrollDirections += ScrollDirection::eVertical;
 *aOutAllowedScrollDirections += ScrollDirection::eHorizontal;

 for (size_t i = 0; i < Length(); i++) {
   if (mChain[i]->CanScroll(aInput)) {
     return mChain[i];
   }

   // If there is any directions we allow overscroll effects on the root
   // content APZC (i.e. the overscroll-behavior of the root one is not
   // `none`), we consider the APZC can be scrollable in terms of pan gestures
   // because it causes overscrolling even if it's not able to scroll to the
   // direction.
   if (StaticPrefs::apz_overscroll_enabled() && bool(aIncludeOverscroll) &&
       // FIXME: Bug 1707491: Drop this pan gesture input check.
       aInput.mInputType == PANGESTURE_INPUT && mChain[i]->IsRootContent()) {
     // Check whether the root content APZC is also overscrollable governed by
     // overscroll-behavior in the same directions where we allow scrolling
     // handoff and where we are going to scroll, if it matches we do handoff
     // to the root content APZC.
     // In other words, if the root content is not scrollable, we don't
     // handoff.
     ScrollDirections allowedOverscrollDirections =
         mChain[i]->GetOverscrollableDirections();
     ParentLayerPoint delta = mChain[i]->GetDeltaForEvent(aInput);
     if (mChain[i]->IsZero(delta.x)) {
       allowedOverscrollDirections -= ScrollDirection::eHorizontal;
     }
     if (mChain[i]->IsZero(delta.y)) {
       allowedOverscrollDirections -= ScrollDirection::eVertical;
     }

     allowedOverscrollDirections &= *aOutAllowedScrollDirections;
     if (!allowedOverscrollDirections.isEmpty()) {
       *aOutAllowedScrollDirections = allowedOverscrollDirections;
       return mChain[i];
     }
   }

   *aOutAllowedScrollDirections &= mChain[i]->GetAllowedHandoffDirections();
   if (aOutAllowedScrollDirections->isEmpty()) {
     return nullptr;
   }
 }
 return nullptr;
}

std::tuple<bool, const AsyncPanZoomController*>
OverscrollHandoffChain::ScrollingDownWillMoveDynamicToolbar(
   const AsyncPanZoomController* aApzc) const {
 MOZ_ASSERT(aApzc && !aApzc->IsRootContent(),
            "Should be used for non-root APZC");

 for (uint32_t i = IndexOf(aApzc); i < Length(); i++) {
   if (mChain[i]->IsRootContent()) {
     bool scrollable = mChain[i]->CanVerticalScrollWithDynamicToolbar();
     return {scrollable, scrollable ? mChain[i].get() : nullptr};
   }

   if (mChain[i]->CanScrollDownwards()) {
     return {false, nullptr};
   }
 }

 return {false, nullptr};
}

bool OverscrollHandoffChain::ScrollingUpWillTriggerPullToRefresh(
   const AsyncPanZoomController* aApzc) const {
 MOZ_ASSERT(aApzc && !aApzc->IsRootContent(),
            "Should be used for non-root APZC");

 for (uint32_t i = IndexOf(aApzc); i < Length(); i++) {
   if (mChain[i]->IsRootContent()) {
     return mChain[i]->CanOverscrollUpwards(HandoffConsumer::PullToRefresh);
   }

   if (!mChain[i]->CanOverscrollUpwards(HandoffConsumer::PullToRefresh)) {
     return false;
   }
 }
 return false;
}

}  // namespace layers
}  // namespace mozilla